1. Field of the Invention
The invention generally relates to communication devices, and more specifically relates to wireless handheld devices that communicate using inductive telemetry.
2. Related Art
Implantable medical devices are becoming increasingly versatile and able to perform many different physiological sensing functions that enable a clinician to quickly and accurately assess patient health. Traditionally, an accurate assessment of patient health required the clinician to synthesize often divergent or seemingly unrelated indications of patient health. For example, a diagnosis of congestive heart failure might include not only an assessment and evaluation of cardiac function data, but also an evaluation of other physiological factors like patient fatigue or respiration data.
Typically, a clinician will assess patient health by inquiring how the patient feels or asking about the patient's activities and then make an indirect assessment based on the patient's response and the clinician's observation of the patient's appearance. However, these measures are very subjective and are limited to the time of the patient/clinician interaction and the quality of patient recall or willingness to divulge information. These factors affect the quality of the assessment.
Modern implantable medical devices offer objective data to help the clinician assess patient health. Modern medical devices can sense and analyze physiological factors with improved accuracy and report that sensed and analyzed information to the clinician or the patient. The data or information that a medical device reports in the form of a sensed physiological parameter can be characterized as either derived or non-derived data. Non-derived data can be understood as raw biometric information sensed by the medical device that has not been clinically analyzed to any meaningful degree. For example, non-derived biometric information may comprise the quantified measurement of a patient's heart rate or blood pressure. In contrast, derived data is biometric information that has been analyzed and perhaps assigned some qualitative value. For example, as a medical device senses a patient's cardiac cycle and clinically analyzes that information, the medical device may report that an arrhythmia has occurred as the result of sensing and analyzing a cardiac rhythm outside expected parameters. Other derived sensors may include the cumulative calories burned by daily activity, a weight loss monitor, a participation in activities monitor, a depression monitor, or determining the onset of cancer, all of which may be ascertained by sensing physiological data and analyzing that data by using clinically derived algorithms or other analytical methods.
Some implanted medical devices may be part of an advanced Patient Management System that includes various physiological sensors and other features to sense and report patient data. Such a system may be adapted to analyze the sensed data in a manner that yields an accurate assessment or prediction of patient health or relative well-being. In this way, the system can be configured to report not only a relative state of patient health, but also alert the clinician to patient health degradation before the onset of an acute episode.
Accurate and reliable reporting and collection of the most relevant data produced by the above-mentioned medical devices and systems has proven to be difficult and cumbersome in many instances. One drawback of many implanted medical devices is their finite memory available for storage of collected data. Some devices include a rolling memory that stores a limited amount of data, which, if not downloaded from the device in a predetermined time period, is dropped from the memory as it is replaced with newer, incoming data.
Typically, a doctor or clinician must perform data retrieval from a medical device or system during a formal visit and evaluation of the patient. Because of the infrequency of these types of patient visits, much of the data collected by the medical device or system is lost before being retrieved and analyzed by the doctor. Of particular concern is the loss of data related to an important physiological event such as heart failure, asthma attacks, etc., whether or not the occurrence of these events are known to the patient.
A data retrieval mechanism that effectively captures relevant physiological data from an implanted medical device or system would be an important advance in the art.